Well flow control method

ABSTRACT

A well flow controlling system and method for a well having a production flow conduit for conducting well fluid from the producing formation to the surface flow lines and a control valve means connected in said production flow conduit and a control fluid conduit connected to said valve means, wherein said control valve means is normally open to permit flow of well fluids through the production flow conduit and is operable to be moved to position closing off the production flow conduit to flow therefrom and to communicate the control fluid conduit with the production flow conduit and the producing formation in the well for closing off flow of well fluids from the well and for loading the well with control fluid when desired to prevent escape of well fluids from the well. A method of operating a well to close off flow of well fluids and to load the well from a remote point by loading fluid or control fluid pressure. Control valve means for use in the system and practicing the method.

United States Patent [1%- Sizer et al.

l l WELL FLOW CONTROL METHOD [75] inventors: Phillip S. Sizer; George G.

Grimmer, both of Dallas, Text [73] Assignee: Otis Engineering Corporatio Dallas, Tex.

[22] Filed: Feb. 8, 1973 [2]] Appl. No.: 330,700

7 Related U.S. Application Data [62] Division of Ser. No. H0372, April 5. 1971.

abandoned.

[52] U.S. Cl. 166/314 [5i] Int. Cl E21b 43/00 [58] Field of Search 166/311, 314 75, 88

[56] References Cited UNITED STATES PATENTS 0710612 lU/l9l0 Holliday l66/3l4 2.!48360 2/1939 Lemley 166/88 3.276.523 lO/l966 Oliver [66/224 3720,264 3/l973 Hutchison l66/3ll f 6/ t 6 5/ 60 7 a r 1 a {Aunt viii. if V, Ii /1471111110),

70 aMs 6 v 6262-62 l a 6 Primary Examiner-James A. Leppink [57] ABSTRACT A well flow controlling system and method for a well having a production flow conduit for conducting well fluid from the producing formation to the surface flow lines and a control valve means connected in said production flow conduit and a control fluid conduit connected to said valve means, wherein said control valve means is normally open to permit flow of well fluids through the production flow conduit and is operable to be moved to position closing off the production flow conduit to flow therefrom and to communicate the control fluid conduit with the production flow conduit and the producing formation in the well for closing off flow of well fluids from the well and for loading the well with control fluid when desired to prevent escape of well fluids from the well. A method of operating a well to close off flow of well fluids and to load the well from a remote point by loading fluid or control fluid pressure. Control valve means for use in the system and practicing the method.

8 Claims, l4 Drawing Figures isms:

Fm snm 3 1975 3,887,611 0 SHEET 1 P l K 5' J fie 5 WELL FLOW CONTROL METHOD This application is a division of application Ser. No. l30,972, filed Apr. 5. l97l, now abandoned.

This invention relates to new and useful improvements in well flow controlling systems, methods and apparatus,

It is one object of the invention to provide a well flow controlling system for controlling production of well fluids from the well producing formation through a well flow conductor to the surface flow lines, by closing off production of such well fluids through the flow conductor to such surface flow lines and simultaneously injecting control or loading fluid into the flow conductor upstream of such closure to load the well to prevent escape of well fluids from the well.

A particular object of the invention is to provide a well flow control system comprising control valve means connected in the well production flow conduit and normally open to permit the flow of well fluids through said production flow conduit to surface flow lines, and a control fluid conduit connected to said control valve normally closed off from communication with the production flow conduit while well fluids are produced through said production flow conduit, said control valve means being movable to a position closing off flow of well fluids therepast to the surface flow lines and opening said control fluid conduit to admit control or loading fluids into the production flow conduit to load the well to prevent escape of well fluids from the well.

A further object of the invention is to provide well flow controlling means of the character set forth wherein the control valve means is operable by the fluid pressure of the control fluid to close off flow of well fluids through the production flow conduit and admit control fluids into the well whereby the flow controlling means is operable from a remote point to prevent escape of well fluids from the well.

A further object of the invention is to provide a well flow control system of the character set forth comprising a plurality of wells, each provided with a well flow control valve means of the character set forth, each of said control valve means connected by control fluid conduit means to a remote source of supply of control fluid and operable by pressure of said control fluid for closing off flow of well fluids from the well to the surface flow line and communicating the control fluid with the well to load the well.

A further object of the invention is to provide a system of the character set forth wherein the plurality of wells connected in the system is each operable selectively and individually from a remote point, whereby any one of said wells in the system may be loaded with control fluid when desired.

A particular object of the invention is to provide means for controlling the flow from a well having a first flow passage therethrough communicating with the well production conduit to permit flow of well fluids from the producing formation to the surface production flow lines and means closing off control fluid conduit from communication with the production fluid conduit, and including a second flow passage means in said control valve means movable to a position closing off flow of well fluids through the valve and opening communication between the control fluid conduit and the production conduit for admitting control fluid into The production conduit to load the well.

An important object of the invention is to provide means for controlling flow of well fluids from a well having a production flow conduit for conducting well fluids from the producing formation to the surface flow lines and a control fluid conduit connected to said production flow conduit, wherein control valve means is connected in said production flow conduit, normally open to permit flow of well fluids through said production flow conduit and connected with said control fluid conduit and closing off flow of fluids from said control fluid conduit from communication with said production flow conduit. said control valve means being movable to a position closing off flow of well fluids therepast to the surface flow lines and opening the control fluid conduit to admit control fluids into the production flow conduit to load the well to prevent escape of well fluids from the well.

Another object of this invention is to provide a two position three-way valve having a well fluid inlet, a well fluid outlet, and a lateral inlet passage. said valve, when in one position, permitting fluid flow therethrough from said well fluid inlet to and through said well fluid outlet and, when in the other position, closing off said well fluid outlet and opening said lateral inlet for flow of fluids between said lateral inlet passage and said well fluid inlet.

Another object is to provide a well flow control valve of the character set forth in which the fluid outlet is closed before the lateral passage is opened.

Another object of this invention is to provide a well control valve of the character described having releasable and yieldable means for maintaining the valve member in position where it will not interfere with normal operation of the well.

Another object is to provide a well control valve of the character described having frangible means holding the valve member in normal position wherein it will not interfere with the normal operation of the well and which can be overcome by application of sufficient force thereto to permit actuation of said valve by application of said fluid pressure thereto.

Another object is to provide a valve of the character described wherein a rupturable partition is interposed between the closure member and the control fluid conduit to prevent the escape of well fluids therethrough and to exclude control fluids from the second flow passage of the closure member.

A further object of this invention is to provide a well control system comprisinga plurality of wells each provided with well flow control means of the character set forth and each such well control means being connected by control fluid conduit means to a remote source of supply of control fluid and wherein pressure actuated valve means are provided between the control fluid conduit means and the flow control means of each well for operating each flow control means in the system individually selectively from a remote point to load any selected well in the system.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIG. 1 is a achematical view of a well head and Christmas tree having therein the flow control apparatus and system for practicing the method for controlling wells in accordance with the invention;

FIG. 2 is a schematical vertical cross-sectional view of the flow controlling valve of the flow control system of FIG. 1;

FIG. 3 is a schematical illustration of a well flow controlling system in which a plurality of wells are connected for control from a single remote control station;

FIG. 4 is a schematical vertical sectional view of a modified form of the flow control valve;

FIG. 5 is an isometrical view of the sealing element for the valve closure member of FIG. 4;

FIG. 6 is an enlarged fragmentary view of a portion of a modified valve closure member similar to the closure member of the valve of FIG. 4;

FIG. 7 is a fragmentary schematical vertical sectional view of a slightly modified form of the valve of FIG. 4;

FIGS. 8 and 9 are schematical illustrations of a rotary plug type valve having a hydraulic operator for actuating the valve to carry out the method of the invention;

FIG. 10 is a schematical vertical sectional view of another form of valve for practicing the method for controlling wells;

FIG. 11 is a horizontal cross-sectional view taken on the line 11 11 of FIG. 10;

FIG. 12 is a cross'sectional view taken through the ball closure of the valve of FIG. 10',

FIG. 13 is a view similar to FIG. 10 showing the valve of FIG. 10 with retaining means therein for positively restraining the ball closure against movement to closing position; and,

FIG. 14 is a schematical vertical sectional view of a further modified form of valve for use in the system of controlling wells.

Referring now to FIG. I of the drawings, a well, generally indicated by the numeral 20, is equipped with a well casing 21 having a wellhead 22 on the upper end thereof to which is attached a Christmas tree 23 comprising a master valve 24, a flow control valve 25 constructed in accordance with the invention, a flow cross 26 and a crown valve or swab valve 27. Wing valves 28 and 29 are connected to the lateral wings of the cross 26 and to at least one of these wing valves is attached a surface flow line 30 which may include conventional flow controlling means such as a choke (not shown). Normally, well products flow upwardly through the tubing or well flow conductor from the producing formation (not shown) to the Christmas tree 23, through the master valve 24, the flow control valve 25, into the cross 26, and outwardly through the one of the wing valves 29 which is open and the surface flow line 30 to conventional handling means (not shown), such as a separator and tank, for disposal. Production from the well may be stopped when desired by closing the wing valve between the well and the flow line but it can also be stopped by closing the master valve 24, if desired.

Upon the occurrence of an emergency or a disaster, such as a fire or hurricane, or an accident, such as a collision, which may rupture, knock off. or destroy the crown valve, cross, wing valve or the surface flow lines, it is desirable that the master valve be closed without undue delay to stop production of the well. This is very important, especially in the case of fire when the escaping well products may add fuel to an already dangerous fire and ignite adjacent wells which may. in turn, add their fuel to enlarge the fire. In such emergency, it may be impossible to approach and close the master valve manually due to the inaccessibility thereof because of the extreme temperatures of the fire. It is therefore desirable to have a flow control valve below the cross operable from a remote point. Even with the well shut in by closing the master valve, the fire may continue for a time and the well is still potentially hazardous because it contains flammable, volatile products at full shut-in well pressure. Extreme heat from the fire can cause the well connections to fail and let the well get out of control. It is desirable in such case to fill the well immediately by loading the production conduit with a non-combustible liquid so there would be no flammable fluids under pressure remaining in the conduit at the surface, so that the well then would be full of water or mud at little or no pressure rather than readily combustible well products at dangerously high pressures. The well flow control valve 25 and the system of which it forms a part provides means for effecting such protection of the well.

One form of the well control valve 25 is illustrated in FIG. 2 wherein the body 36 is provided with a flow passage 37 therethrough and attaching means such as flanges 38 and 39 at the upper and lower ends thereof, respectively, for securing the valve in a well Christmas tree, preferably immediately above the master valve, to permit repairing or replacing any part of the Christmas tree thereabove after closing the master valve which normally remains open and is closed only when absolutely necessary.

The body 36 is also provided with a transverse bore 40 which intersects the flow passage 37 intermediate its ends to divide the same into upstream and downstream portions 37a and 37b, respectively.

A closure member 41 is slidably disposed in the transverse bore 40 and is provided with a first flow passage 4la therethrough which, when the closure member is in the position shown in FIG. 2, is aligned and continuous with the upstream and downstream portions 37a and 37b of the body flow passage 37 and permits fluid flow through such flow passage.

One end of the closure member 41 is reduced as at 41b to provide a stem which extends through the aperture 42a of a bonnet 42 having an external annular flange 42b fastened in the conventional manner, as by stud bolts (not shown), to the valve body to close such end of the transverse bore.

A coiled spring 43 surrounds the stem 41b and is confined between the shoulder 41c on the closure member at the inner end of the stern and the bottom of the counterbore 42c in the bonnet for yieldably biasing the closure member towards the position shown in FIG. 2. The spring thus tends to maintain the closure member in a position wherein its first flow passage 41a is aligned with the flow passage 37 of the body to permit normal operation of the well. Movement of the closure mem ber by the spring is limited by the engagement of the opposite end surface 41d of the closure member with a stop shoulder 440 formed by the inner end of a control fluid conduit 44 threaded into the threaded end 44b of the transverse bore of the body. Movement of the closure member in the opposite direction is limited by the engagement of the shoulder 41c at the base of the stem with the shoulder 42d provided by the inner end of the bonnet at the counterbore 42c.

The closure member 41 is further provided with a second L-shaped flow passage Me which comprises a vertical branch 41f and a horizontal branch 41g. The vertical branch opens downwardly of the closure member while the horizontal branch opens longitudinally outwardly through the end of the closure member opposite the stem 41b and communicates at all times with the transverse bore 40 of the body.

A resilient seal ring 45a is disposed in a horizontally disposed groove formed in the upper portion of the transverse bore 40 of the body and surrounding the downstream portion 37b of flow passage and a resilient seal ring 45b is disposed in a similar horizontally disposed groove formed in the lower portion transverse bore and surrounding the upstream bore portion 37a to confine fluid flow through the valve body tothe flow passage 37 and the first flow passage 410 or through the upstream bore portion 370 and the second flow passage 41a of the closure member, and to the control fluid conduit 44. The seal rings 45a and 45b also prevent cross flow between such first and second flow passages.

The closure member is movable from the position shown in FIG. 2 to the left until the shoulder 41c thereof engages the bonnet and the first flow passage 41a is out of flow communication with flow passage 37 of the body. In this position, the second flow passage 4le is in direct flow communication with the upstream portion 37a of the body flow passage while, at the same time the downstream portion 37b is closed by the closure member and the seal ring 450. The valve 35 is now closed to the flow of well fluids upwardly to the flow cross and surface flow lines, while the second flow passage 4le of the closure member communicates the upstream bore portion 37a of the body with the control fluid conduit 44, and control fluids are readily introduced into the well to displace the well fluids therein into the producing formation and fill or load the well flow conduit with control fluid. such as mud or water. Thus, the flammable, volatile well fluids are forced back into the formation whence they came and are replaced by heavier, noncombustible mud or water. This reduces the surface pressure, preferably to that of the atmosphere.

During movement of the closure member between the two positions just described, the spring chamber formed by the counterbore 42c of the bonnet and transverse bore 40 of the body is allowed to breathe through a downwardly facing vent or aperture 42e formed in the wall of the bonnet. Thus. the pressure in the spring chamber always readily equalized with pressure exteriorly of the valve.

The control fluid conduit 44 (see FIG. 1) is connected to a pump P driven by a motor M and having a suction line S connected to a source of control fluid such as tank T. The conduit 44 may have a valve V connected therein and preferably has a back flow check valve C therein near or adjacent the control valve 25.

When it is desired to load or kill the well with control fluid, the motor M is utilized to drive the pump P which picks up control fluid from the tank T through the suction line S and forces such control fluid under pressure through the conduit 44, including the valve V and check valve C, into the transverse passage 40 where it acts on the cross-sectional area of the valve closure member in opposition to the force of spring 43 and the pressure in the spring chamber to mo e the closure member toward the left to a position in which the first flow passage 41a is out of flow communication with the flow passage 37 of the body and the second flow passage is disposed with its vertical portion 41b in flow communication with the upstream portion 37a of the body. In this position, control fluids will flow through the second flow passage 41c into the upstream portion 37a of the body and the well flow conductor connected therebelow.

Non-combustible control fluids are thus introduced into the upper end of the well flow conductor to load or kill the well by displacing the flammable fluids downwardly therefrom. Back flow of control fluids through the control fluid conduit from the well is prevented by the back flow check valve C.

To more positively retain the valve closure member in the normal open position shown in FIG. 2 and avoid interfering with the usual operation of the well until it is desired to load the well with control fluid, a shear pin 46 may be disposed in aligned apertures in the stem 41b and in the boss 42b of the bonnet. Then, before the closure member can be moved from the normal open position shown in FIG. 2, the force of control fluid pressure applied thereto must overcome and shear the pin 46. Obviously, the diameter of shear pin 46 and the material from which it is made may be so selected as to provide the shear value desired and where unusually high shear values are required, multiple shear pins can be used, each pin being disposed'in a separate set of apertures in the stem and bonnet.

It will be noted that, when the closure member 41 is in the position shown in FIG. 2, the outer end of the stem 41b is substantially flush with the outer end of the bonnet 42. When the closure member has been moved to a position allowing loading the well with control fluids, as before explained, the stern will protrude a considerable distance from the bonnet. Thus, the stem readily indicates the position of the closure member within and relative to the body.

While the well 20 in FIG. 1 is shown to include a well control valve 25 operated by pressurized control fluid supplied thereto through control fluid conduit 44 from tank T by pump P, several wells, each equipped with such a flow control valve, can be served more economi cally by a common source of pressurized control fluid. In such a system the control fluid conduit 44 is provided with a valve V connected in such control fluid conduit near or adjacent the flow control valve 25, so that the source of pressurized control fluid can be connected to any selected one or more of such plurality of wells in the system. When these valves in the control fluid conduit are remotely operable. then any selected well in the system may be loaded when desired, as in the case of a fire, without the necessity of anyone approaching the well.

Such a well flow control system is illustrated diagrammatically in FIG. 3, wherein five wells, 20a through 20e, are shown to be connected in the system, though it could comprise any number of wells. These wells are equipped with flow control valves 250 through 25a, respectively, connected by a common control fluid conduit 44 to a. pump P which is driven by motive means M and picks up control fluid from tank T through the suction conduit S.

The common control fluid conduit 44 includes five branch conduits, 440 through 44a, which are connected to flow control valves 25a through 25: respectively. The five branch conduits are provided with valves Va through Vc having remotely controlled valve operator devices 50a through 502, respectively, for opening and closing the corresponding valves Va through Ve to selectively operate any selected one or more of the valves to load such selected well or wells with control fluid. Thus, if it is desired to load well 20a with control fluid, the valve Va is actuated to open position while valves Vb through Ve remain closed. Control fluid is then forced by the pump P through the common conduit 44 and branch conduit 44a to the control valve 25a to move it to well loading position, after which continued pumping of control fluid will load the well in the manner already described.

The valve operator devices 500 through 50e may be of the type illustrated and described in U.S. Pat. No. 3,444,783 to Fredd, and are operated by hydraulic pressure, being selectively unlockable and operable from a remote station connected to the system by a single pair of hydraulic fluid conduits. The operator devices respond to a pressure pulse code signal comprising a series of discrete and discontinuous pressure pulses transmitted thereto through the pair of hydraulic fluid conduits. Thus, a proper series of pressure pulses will unlock only the proper operator device in the system and subsequent application of hydraulic fluid pressure of ample magnitude will actuate the valve which it operates.

The control station K includes means (not shown) such as hydraulic pump, oil, reservoir, valving, pressure gauges, etc. for generating the proper pulse code signals and transmitting them through the hydraulic conduits 51 and 52 to the five operator devices 500 through 50e which control the valves Va through Ve, respectively. The hydraulic conduit 51 is connected to the operator devices 50a through 50e by hydraulic branch conduits 51a through le and, similarly, hydraulic conduit 52 is connected to the operator devices by hydraulic branch conduits 52a through 53c, respectively.

If all of the wells a through 202 are flowing, with the valves Va through Ve closed, and it is desired to load well 200 with control fluid, the control station K is operated to pressurize the hydraulic conduits 51 and S2 to transmit a discrete pressure pulse code signal designed to actuate the operator device 50a and no other in the system. The other operator devices will receive such coded pressure signals but the response will be that of continually zeroing or resetting the lock mechanisms thereof to the starting point with each successive signal and so preclude unlocking all but the selected valve. Upon unlocking the operator device 50a, hydraulic pressure is applied thereto to actuate the valve Va to open position, after which, the motive means M is actuated to drive the pump P to pick up control fluid through suction conduit S from tank T and deliver it under pressure through the common control fluid conduit 44 and the branch conduit 44a and the valve Va to the control valve 250. The pressure of the control fluid then forces the closure member of the control valve to a position stopping production of well fluids from the well by closing the downstream portion of the valve flow passage and wherein the second flow passage of the closure member communicates with the well flow conductor for admitting control fluid into the well.

Pumping of control fluid is continued until the well is loaded and properly under control. At this time, the pump is stopped and the proper pulse code signal is generated by the station K and transmitted to the operator device 50a to unlock the device, permitting hydraulic pressure to then actuate the control fluid conduit valve Va to closed position to prevent possible back flow of control fluid from the well through the control fluid conduit. lf desired, a back flow check valve also may be provided on the branch conduit 440 between the control valve 25a and the valve Va for the purpose of preventing such back flow of control fluids from the well.

In the same manner, any other well in the system can be loaded with control fluids and all of the wells may be so loaded with control fluid in any order desired.

A slightly modified form of well control valve 55 is illustrated in FIG. 4, and includes a body 56 having a vertical flow passage 57 therethrough and the useful flanges S8 and 59 for securing the valve in a well Christmas tree. The body 56 is also provided with a transverse bore 60 which intersects the flow passage 57 intermediate its ends to divide the same into upstream and downstream portions 57a and 57b, respectively.

A cylindrical closure member 61 slidable in the transverse bore 60 ha a first flow passage 61a therethrough which, when the closure member is in the position shown in FIG. 4, is aligned and continuous with the upstream and downstream portions 570 and 57b of the body flow passage 57 and will permit fluid flow through such passage. One end of the closure member is reduced in diameter to provide a stem 61b which extends through the aperture 62a of the bonnet 62 secured by a flange 62b to the valve body to close one end of the transverse bore therein.

A coiled spring 63 surrounds the stem 61b and is confined between the shoulder 610 on the closuremember at the inner end of the stem and the bottom of the counterbore 62c in the bonnet for yieldably biasing the closure member toward the normally open position shown in FIG. 4. The spring thus tends to maintain the closure member in a position wherein its first through flow passage 61a is aligned with the flow passage 57 of the body to permit normal operation of the well. Movement of the closure member by the spring is limited by the engagement of the opposite end surface 61d of the closure member with a stop shoulder 67a provided by the rupture disk 67 which is secured in an outer threaded counterbore portion 60b of the transverse bore by a bushing 68 threaded int the counterbore.

The periphery of the desk 67 is tightly held between the bottom of the counterbore and the end 680 of the bushing tightened thereagainst. A control fluid conduit 69 i threaded at 69a into the bushing so that the bore 6% of the conduit is in constant communication with the bore of the bushing. The disk 67 thus prevents the passage of fluids between the control fluid conduit 69 and the transverse bore of the valv 55 until the disk is ruptured in a manner and for a pupose to be described.

In order to more positively retain the valve closure member in the open position shown in FIG. 4 to avoid interfering with the normal operation of the well until a condition develops which would make it desirable to load or kill the well, a shear pin 70 is disposed in aligned transverse apertures in the outer portion of the stem 61b and in the boss 62d of the bonnet. Then, before the closure member can be moved from the position shown in FIG. 4, the force applied thereto must shear the pin 70. It is obvious that the shear value of the shear pin 70 may be varied by varying the size of the pin and the material from which it is made. In addition. a plurality of shear pins may be used in a plurality of sets of aligned apertures if large forces are to be withstood.

In this form of the flow control valve, like that of FIG. 2, the outer end of the stem 61!; is flush with the outer end of the bonnet 62 when the valve closure member is in the normal open flow position shown, and that, when the closure member is moved to the second position (not shown) wherein the vertical portion 610 of the second passage 61b is aligned with the upstream portion 570 of the body flow passage, the outer end of the steam will project from the bonnet a noticeable distance. This position of the steam readily indicates to an observer the position of the valve closure member within the valve body.

A vent or breather hole 62a is provided in the wall of the bonnet to permit the spring chamber formed by the counterbore 62s of the bonnet and the transverse bore 60 fo the body to breathe so that the pressure therein will readily equalize with the environment.

The cylindrical valve closure member 61 is provided with three longitudinal spaced external annular seal recesses or grooves; one between the vertical portion 61a of the second flow passage and the right hand end of the valve closure member, one between the first and second flow passages. and one between the first flow passage and the stem. The two outermost seal recesses are connected together by a pair of diametrically opposite longitudinal grooves spaced substantially equally circumferentially between the opposite ends of the first flow passage. This system of seal recesses, indicated generally by the numeral 7l, receives a resilient seal member 72 shown in detail in FIG. 5. The seal member 72 comprises three axially spaced ring portions 72a, 72b and 720 which are connected together by a pair of diametrically opposed parallel longitudinal straight portions 72d and 72e. When the seal member is in place in the seal recesses, the ring portions 721; and 720 seal between the valve closure member and the body on either longitudinal side of the first flow passage 61a. When the closure member is moved to its second position for loading the well with control fluid, the vertical portion 6le of the second flow passage 61b is aligned with the upstream portion 570 of the body flow passage and the seal ring portions 720 and 72b seal between the closure members and the body on either side of the vertical portion of the second flow passage. The straight portions 72a and 72a of the seal member prevent the leakage of fluids circumferentially around the cylindrical closure member between the seal ring portions. Thus, the fluids flowing through the valve are at all times confined to the proper flow passages.

Since the closure member is cylindrical, it is provided near its shoulder 61c with a key seat 6111 in which a key 73 is disposed for slidable engagement in a keyway 56a formed in the wall ofthe transverse bore 60 of the valve body to prevent rotation of the closure member about its longitudinal axis and assuring proer orientation of the flow passages of the closure member with the flow passage 57 in the body.

When it is desired to load the well, pressurized control fluids applied through control fluid conduit 49 act against the rupture disk 67. When the disk ruptures, pressurised control fluid is admitted into the valve and acts against the cross-sectional area of the closure member 61 and this force, if of sufficient magnitude, moves the closure member to the left, as seen in FIG. 4, shearing the pin 70 and compressing the spring 63. Leftward movement of the closure member in the body is limited by engagement of the shoulder 61c of the closure member with the bonnet 62. In this position, the second flow passage of the closure member is aligned with the upstream portion 57a of the body flow passage and control fluids can flow into the well flow conduit to load the well as previously described.

It should be understood that the vertical portion 6le of the second flow passage is spaced from the first flow passage 61a of the closure member a distance sufficient to permit the first flow passage to move out of fluid communication with the body flow passage prior to movement of said second flow passage into flow communication with said body flow passage when the valve is actuated for loading the well. Thus, control fluids will not be permitted to flow from the second tothe first flow passage and escape upwardly through the downstream portion 57b of the body flow passage.

The rupture disk is shown in FIG. 4 to be carried by the body; but, if desired, a rupture disk can be carried by the closure member instead. The closure member 75, shown fragmentarily in FIG. 6, is identical to the closure member 61 of FIG. 4 except that the outer end of its second flow passage 76 is counterbored at 76a and a rupture disk 77 is sealingly secured therein in any suitable means, such as by welding, bonding, etc.

When the closure member is used in a valve such as the valve 55, the pressurized control fluid utilized to move the closure member causes said clsoure member to be moved to position for loading the well with control fluid before the disk ruptures, thus assuring that the closure member is in proper position before the second flow passage is unsealed.

A further modified form of the flow control valve is illustrated fragmentarily in FIG. 7, being indicated generally by the numeral 80. This valve is very similar to the valve 55 previously described and functions in the same manner, but the spring chamber 80a is vented to the first flow passage 61q of the valve closure member 61m rather than being vented to the atmosphere or region exterior to the valve. It will be seen that a seal ring or O-ring 81 disposed in an internal annular groove 62f in the outer end of the bore of the bonnet 62g sealingly engages the stern 61k of the closure member to prevent the escape of well fluids outwardly between the stem and the bonnet. An equalizing flow passage 6ln is formed in the closure member with one end opening through the shoulder 61p at the base of the stem 61k and the other end opening into the first flow passage 6lq of the closure member. Thus, the pressure in the spring chamber 81a readily equalizes with the pressure in the first flow passage of the closure member because of the constant fluid communication through such equalizing flow passage.

Another form of the flow control valve is illusturated in FIGS. 8 and 9. In this form the valve is a threeway plug valve which may be installed in the Christmas tree in place of the flow control valve 25 of FIG. 1. The valve 90 has a body 91 with a main flow passage 91a for conducting well fluids through the valve during normal operation of the well on which it is installed, and a lateral control fluid passage 91b intersecting the main flow passage. At this intersection of these two passages the body is formed a transverse bore 910 in which a rotary plug type closure member 92 is mounted for rotational movement in the conventional manner. The closure member 92 has a first flow passage 920 which, in the normal open position of the valve shown in FIG. 8, is aligned with the main flow passage 91a of the body and will allow normal production operation of the well. When the closure member is moved to the closed position shown in H6. 9, the first flow passage 92a is aligned with the lateral control fluid flow passage 91b of the body, and the upper or downstream portion 91d of the body flow passage is closed off. The lower or up stream portion 91c of the body passage then communicates with a lateral second flow passage 92bin the closure member which intersects the first flow passage 92a therein medially at an angle of 90 to the first flow passage, which is then in communication with the lateral flow passage 91b of the body.

A control fluid conduit 93 is connected at one end to the outer end (not shown) of the lateral flow passage 91b and at its other end is connected to a pump P having a suction line or conduit 930 connected to a tank T in which control fluid is stored. Motive means such as the motor M drives the pump.

The plug type closure member 92 is rotatable in the conventional manner by means of an external handle 94 attached to one end of the plug.

A hydraulic operator 95 is mounted on or near the valve 90 and has the usual reciprocating piston (not shown) therein and a piston rod 95a extending from one end thereof and attached to the valve handle 94 for rotating the valve closure means between the open position shown in FIG. 8 and the closed position shown in FIG. 9.

The end of the hydraulic operator opposite that from which the piston rod extends is connected to the control fluid conduit 93 by a branch flow conduit 93b. Thus, when it is desired to load the well with control fluid, the motor M is actuated to drive the pump P which picks up control fluid from the tank T through the suction conduit 930 an delivers such control fluid to the well under pressure. Pressurized control fluid from conduit 93 enters the cylinder of the operator 95 through the branch conduit 93b and moves the piston therein (not shown) to extend the piston rod 95a and swing the handle 94 to rotate the valve closure member from the open position shown in FIG. 8 to the closed position shown in FIG. 9.

When the valve is closed, as shown in FIG. 9, the escape of well fluids from the well is precluded by the closing of the downstream portion 91d of the main flow passage of the body by the closure member. Also, the pressurized control fluid from conduit 93 enters the valve body 91 through lateral passage 91b, flows through a portion of the first flow passage 92a and then through the second flow passage 92b and through the lower or upstream portion 91a of the body into the master valve and well conduit therebelow. Control fluids may thus be pumped into the well until the desired loading is effected.

A still further form of flow control valve 100 is illustrated in FIGS. through 13 and comprises a T- shaped body 101 having attaching means such as flanges 102 and 103 at its upper and lower ends, respectively, and 108 on its lateral wing 101a, for connecting the valve in a well Christmas tree, as between a master valve 104 and a flow cross 105, and with a control fluid conduit 109, respectively. The body has a main flow passage 106 which is continuous with the flow passages 104a of the master valve and 105a of the flow cross, for conducting well fluids through the valve during normal operatioin of the well, and a lateral flow passage 107 in the lateral wing 1010 which at its inner end intersects the main flow passage 106 intermediate its ends. The outer end of the lateral flow passage opens through the flange 108 into the control fluid conduit 109, to connect the bore 109a of such conduit in direct fluid communication with the lateral flow passage 107 of the body.

The lateral flow passage 107 curves arcuately upwardly as its intersects with and blends into the main flow passage 106, and as is clearly shown in FIG. 10, the main flow passage 106, at the intersection with the lateral flow passage and for a short distance thereabove is enlarged to the same diameter as the lateral passage, thus providing an arcuate bore 110 in which a valve closure member such as a ball 111 is movable in a man ner to be described.

The enlargement of the main flow passage 106 provides a downwardly facing shoulder or seat surface 1 12 near the upper end of the body 101 adapted to be engaged by the ball 11] for closing the main flow passage to prevent upward flow of well fluids therepast. The end of the bore 109a of the control fluid conduit 109 is chamfered to provide a seat surface 10912 engageable by the ball 11] to prevent the escape of well fluids outwardly therepast into the control fluid conduit 109.

The control fluid conduit is connected to a source of pressurized control fluid in the manner previously described, so that the well on the flow control valve is installed may be loaded with control fluid when desired.

During normal opeation of the well, the ball 11] remains in engagement with thet seat surface 10% formed at the end of the control fluid conduit since the well pressure in the body ordinarily exceeds that in the control fluid conduit, which may be as low as environmental pressure. The main flow passage 106 of the valve is open to the flow of well fluids therethrough from the master valve 104 to the flow cross in the usual manner of producing a well.

When it is desired to stop production of the well and to load or kill the well, control fluid at elevated pressure is delivered to the well from the source of supply (not shown) through the control fluid conduit 109. The pressurized control fluid will overcome the force of well pressure acting on the ball 111 and force the ball from engagement with the seat surface 10% and move it into the stream of well fluids flowing upwardly through the main flow passage 106 of the body. The ball is then immediately lifted into intimate engagement with the seat surface 112 and will shut off the flow of well fluids upwardly therepast. The pressurized control fluid entering the body through the lateral passage 107 will then flow downwardly through the lower portion 106a of the main flow passage. through the bore 1040 of the master valve 104 and into the well flow conductor (not shown) therebelow to load the well with non-combustible control fluid, as before explained.

The spherical closure member or ball 111 may be made of any suitable material such as steel, brass, plastic or like material, and may be solid or hollow. In many cases it may be desirable to form the ball with a solid or hollow metal core and bond a resilient covering to the exterior thereof. One preferred form of the ball 11] is illustrated in FIG. 12, wherein the core llla of the ball is solid metal and the covering lllb is a resilient and abrasion resistant material such as synthetic rubber or polyurethane, preferably the latter.

In cases where equipment such as wire line tools, instruments or the like. are to be run into the well through the flow control valve 100, it is desirable to positively hold the ball 111 out of the main flow passage 106 through the body, so that it will not interfere with the passage of such tools through the valve. A sleeve 120 for so excluding the ball from the main flow passage is shown in FIG. 13, having a bore 120a and an internal annular recess 120k formed near its upper end for the engagement of a running in and retrieving tool (not shown) used for setting the sleeve in position within the valve body 101 and for removing the sleeve therefrom. The sleeve is formed with a plurality of inverted U-shaped slots 1206, each defining upwardly extending resilient detent finger 120d having its upper end inherently sprung outwardly. so that the group of fingers will span a diameter greater than that of the main flow passage above the seal suruface 112. The detent fingers are contractible upon engaging a restriction in the Christmas tree above thte master valve to permit lowering the sleeve therepast on the running in tool until the beveled lower end 120e of the hsleeve engages the upper end of the bore 104a of the master valve 104 to limit downward movement of the sleeve. In this position, the upper ends of the fingers 120d have passed through the upper portion 106b of the main flow pas sage 106 and have sprung outwardly in the enlarged bore 110 below the seat surface 112 to a position ready to engage the downwardly facing seat surface 112 should the sleeve be lifted. When the running tool is released and withdrawn from the Christmas tree, the sleeve 120 remains in the main flow passage 106 of the body and will prevent the ball 111 from moving inwardly from the lateral passage 107 to a position in the passage 106 where it would interfere with the movement of tools through the bore 120a and the main flow passage of the valve.

When it is desired to remove the sleeve 120 from the valve, :1 retrieving tool (not shown) of well-known type is lowered through the Christmas tree and into the sleeve to engage and lock in the internal recess 120a thereof. The sleeve is then lifted, and the upward movement of the sleeve causes the inclined surface of seat 112 to engage the upper ends of the detent fingers 120C and cam them inwardly to pass the seat and permit the sleeve to be lifted through the restricted portion 1|)6b of the body main flow passage and through the Christmas tree for complete removal from the well.

A modified form of the last described flow control valve is illustrated in FIG. 14, wherein the valve 150 comprises a body 131 having conventional flanges 132 and 133 at its upper and lower ends for attaching the valve in a well Christmas tree between a crown valve 134 and a master valve 135. A main flow passage 136 in the body is aligned and continuous with the bore 134a of the crown valve and bore 1350 of the master valve.

The body 131 is also formed with a transverse flow passage 137, the outer end of which opens through a flange 138 which connects to a wing valve 139 which in turn is connected to the usual flow line (not shown) for conducting \vcll fluids from the Christmas tree to conventional handling lacilltlcs such as a separator, tank. etcv The inner end of the transverse flow passage 137 intersects the main flow passage intermediate its ends in exactly the same manner as did the transverse flow passage of the valve previously described, and curves upwardly and blends with such main flow passage in the same manner. Tl-le inside diameter of the transverse passage 137 and the enlarged portion 136a of the main passage is greater than the inside diameter of the lower portion l36b of the main passage below the intersectron.

The valve body 131 is provided with a control fluid passage wing 140 having a flow passage 140a which extends downwardly from the transverse flow passage 137 substantially parallel to the main flow passage 136. Its lower end opens through a conventional flange 141 which is connected to a control fluid conduit 142 extending to the well froma source of pressurized control fluid like that previously described.

The lower end of the control fluid flow passage 1400 is counterbored as at 140!) to receive a rupture disk 143 which is sealed by welding, or bonding or the like, and is further retained by the connection of flanges 141 of the wing 140 and the control fluid conduit 142. Thus, fluid flow cannot take place past the disk 143 as long as it remains intact, and well fluids cannot enter the control fluid conduit from the well, nor can control fluid enter the well from the conduit 142.

The control fiuid passage 140a in the wing 140 is sufficiently long to receive and house two spherical closure members or balls 144a and 144b, like the ball 111, which are supported by the rupture disk and do not interfere with the normal operation of the well. Well fluids flow upwardly through the bore 135a of the master valve 135, through the lower portion 136b of the main flow passage 136, through the transverse flow passage 137 and the wing valve 139 to the flow line (not shown).

Vertical access into the well by well tools and the like may be had through the bore 1340 of the crown valve 134, the main flow passage 136 of the valve 130, and the bore 135a of the master valve 135.

If desired. a sleeve like the sleeve previously described may be disposed in the main passage 136 to exclude the balls 144a and 144i) therefrom to prevent them from interfering with the passage of tools through the main flow passage.

The two balls 144a and 14419 are adapted to engage the seating surfaces 13412 formed around the lower end of the bore 134a of the crown valve 134 and a like seat surface 139a formed around the bore 139!) of the control fluid conduit 139.

When it is desired to load the well on which the flow control valve is mounted, pressurized control fluid overcomes the resisting force of the disk 143 and caues it to rupture, and the upward flow of control fluid in the control fluid passage a lifts the two balls 144a and 144b ni such passage. The ball 144a enters the transverse flow passage 137 and if well fluids are flowing therethorugh into the wing valve 139, the ball 144a will be forced against the seat surface 13% of the wing valve to close the bore 13% thereof against the escape outwardly of both well fluids and control fluids. The ball 14417 is then lifted into the passage 137 and, since the passage in the wing valve 139 is now closed by the ball 1440, the ball 144k moves toward the main flow passage 136; and, if flow is taking place upwardly through the crown valve 134, the ball 144b will e lifted by such flow into engagement with the seat surface 13417 to close the bore 134a of the crown valve against further escape of fluids upwardly therethrough.

Both paths of escape being closed, additional control fluids entering the valve 130 from the control fluid con duit 142 will flow downwardly through the lower por tion 136k of the main flow passage and through borc 1350 of the master valve into the well flow conductor (not shown) therebelow to load the well with noncombustible fluid.

It should be understood that the seal surface l34h, while shown on the lower end ofthe crown valve. could as well be formed in the main flow passage [36 of the valve 130 in the same manner that the seat surface 112 was formed in the main flfow passage 106 of valve 100.

It is also readily apparent that either of the balls 144a and 144!) can engage either of the seats l34b and 139a, and that neither of them is able to close the lower portion l36b of the main flow passage 136 to prevent loading of the well with control fluids, since the opening at the junction of such passages is an oval.

It will, therefore, be seen that control valve means have been provided which are arranged to permit the introduction of control or loading fluid through said control valve means into the well flow conductor after the main flow passage through the control valve passages have been closed to prevent the escape of well fluids from the well through the Christmas tree. Also, that such control valvle means are automatimcally operable by the control fluid which is then introduced into the well to load the flow condenser with noncombustible fluid and so eliminate the danger of uncontrolled escape of combustible well fluids from the well and the attendant hazards of tire, high fluid pressures, and the like. It will also be seen that the apparatus and system is operated and controlled from a remote point.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, withtin the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to secure by Letters Patent is:

l. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation through a Christmas tree having a control valve connected therein to a production flow line at the surface, said method including: producing well fluids from the well producing formation through the flow conductor and the Christmas tree to the production flow line; automatically closing off flow of well fluids from the well flow conductor to the surface production flow line; and introducing control fluid under pressure into said well flow conductor upstream of said closure while flow is closed off from the surface production flow line to load the well to prevent the escape of well fluids from the formation through the flow conductor.

2. A method of the character set forth in claim 1 including: closing off the well flow conductor in the Christmas tree and introducing control fluid from a remote point under pressure into the well flow conductor at a point upstream in said Christmas tree from said closure.

3. A method of controlling flow from a plurality of wells, each having a flow conductor therein for conducting well fluids from a producing formation to a production flow line at the surface through a Christmas tree having a control valve therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing each of said wells separately to flow well fluids from the producing formation through the flow conductor and the through flow passage of the Christmas tree to the surface production flow line; selectively closing off flow of well fluids from one or more selected ones of the wells from the flow conductor to the surface production flow line at a point upstream of the surface flow line and downstream of said lateral control fluid passage; and introducing control fluid under pressure through said lateral passage of said control valve to open said lateral passage and admit such control fluid into said well flow conductor upstream of the point at which flow of well fluids from the flow conductor to the surface production flow line is closed off to load the selected one or more wells with control fluid to prevent escape of well fluids from such one or more wells.

4. A method of the character set forth in claim 3 wherein the step of controlling the closing off of flow from the producing formation through the flow passage of the Christmas tree downstream of the through flow passage of the control valve in the Christmas tree and introducing control fluid under pressure through the lateral passage of said control valve into the flow conductor upstream of said closure is controlled from a remote point.

5. A method the character set forth in claim 3 wherein the step of closing off flow of well fluids from the well flow conductor through the Christmas tree to the production flow line and introducing control fluid under pressure into said flow conductor of said well upstream of said closure is selectively controlled from a remote point to permit such operation of from one to all of such plurality of wells.

6. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation to a surface production flow line through a Christmas tree having a flow path therethrough and having a control valve connected therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing well fluids from the well producing formation through the flow conductor and the flow path through the Christmas tree to the surface production flow line; introducing control fluid under pressure into said lateral control fluid passage of the control valve to operate said control valve to close off flow of well fluids through the flow conductor and the flow path through the Christmas tree to the surface production flow line at a point downstream of said lateral control fluid passage of said control valve and to establish communication of said lateral control fluid passage of said control valve with the flow path of the Christmas tree upstream of the closure and with the flow conductor; continuing introducing of control fluid through said lateral control fluid passage into the flow conductor to load the well with control fluid to prevent escape of well fluids from the well producing formation through said flow conductor.

7. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation to a surface production flow line through a Christmas tree having a flow path therethrough and having a control valve connected therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing well fluids from the 'well producing formation through the flow conductor and the flow path through the Christmas tree to the surface production flow line; introducing control fluid under pressure into said lateral control fluid passage of the control valve to operate said control valve automatically by such control fluid pressure to close off flow of well fluids through the flow conductor and the flow path through the Christmas tree to the surface production flow line at a point downstream of said lateral control fluid passage of said control valve and to establish communication of said lateral control fuid passage of said control valve with the flow path of the Christmas tree upstream of the closure and with the flow conductor; continuing introducing of control fluid through said lateral control fluid passage into the flow conductor to load the well with control fluid to prevent escape of well fluids from the well producing formation through said flow conductor.

8. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation to a surface production flow line through a Christmas tree having a flow path therethrough and having a control valve connected therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing well fluids from the well producing formation through the flow conductor and the flow path through the Christmas tree to the surface production flow line; introducing control fluid under pressure into said lateral control fluid passage of the control valve to operate said control valve automatically by such control fluid pressure to close offflow of well fluids through the flow conductor and the flow path through the Christmas tree to the surface production flow line at a point downstream of said lateral control fluid passage of said control valve and to establish communication of said lateral control fluid passage of said control valve with the flow path of the Christmas tree and with the flow conductor; continuing introduction of control fluid through said lateral control fluid passage into the flow conductor; directing control fluid introduced into said flow conductor downwardly by means of said closure through said flow conductor to the well producing formation to load the well with control fluid to prevent escape of well fluids from the well producing formation through said flow conductor. 

1. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation through a Christmas tree having a control valve connected therein to a production flow line at the surface, said method including: producing well fluids from the well producing formation through the flow conductor and the Christmas tree to the production flow line; automatically closing off flow of well fluids from the well flow conductor to the surface production flow line; and introducing control fluid under pressure into said well flow conductor upstream of said closure while flow is closed off from the surface production flow line to load the well to prevent the escape of well fluids from the formation through the flow conductor.
 1. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation through a Christmas tree having a control valve connected therein to a production flow line at the surface, said method including: producing well fluids from the well producing formation through the flow conductor and the Christmas tree to the production flow line; automatically closing off flow of well fluids from the well flow conductor to the surface production flow line; and introducing control fluid under pressure into said well flow conductor upstream of said closure while flow is closed off from the surface production flow line to load the well to prevent the escape of well fluids from the formation through the flow conductor.
 2. A method of the character set forth in claim 1 including: closing off the well flow conductor in the Christmas tree and introducing control fluid from a remote point under pressure into the well flow conductor at a point upstream in said Christmas tree from said closure.
 3. A method of controlling flow from a plurality of wells, each having a flow conductor therein for conducting well fluids from a producing formation to a production flow line at the surface through a Christmas tree having a control valve therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing each of said wells separately to flow well fluids from the producing formation through the flow conductor and the through flow passage of the Christmas tree to the surface production flow line; selectively closing off flow of well fluids from one or more selected ones of the wells from the flow conductor to the surface production flow line at a point upstream of the surface flow line and downstream of said lateral control fluid passage; and introducing control fluid under pressure through said lateral passage of said control valve to open said lateral passage and admit such control fluid into said well flow conductor upstream of the point at which flow of well fluids from the flow conductor to the surface production flow line is closed off to load the selected one or more wells with control fluid to prevent escape of well fluids from such one or More wells.
 4. A method of the character set forth in claim 3 wherein the step of controlling the closing off of flow from the producing formation through the flow passage of the Christmas tree downstream of the through flow passage of the control valve in the Christmas tree and introducing control fluid under pressure through the lateral passage of said control valve into the flow conductor upstream of said closure is controlled from a remote point.
 5. A method the character set forth in claim 3 wherein the step of closing off flow of well fluids from the well flow conductor through the Christmas tree to the production flow line and introducing control fluid under pressure into said flow conductor of said well upstream of said closure is selectively controlled from a remote point to permit such operation of from one to all of such plurality of wells.
 6. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation to a surface production flow line through a Christmas tree having a flow path therethrough and having a control valve connected therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing well fluids from the well producing formation through the flow conductor and the flow path through the Christmas tree to the surface production flow line; introducing control fluid under pressure into said lateral control fluid passage of the control valve to operate said control valve to close off flow of well fluids through the flow conductor and the flow path through the Christmas tree to the surface production flow line at a point downstream of said lateral control fluid passage of said control valve and to establish communication of said lateral control fluid passage of said control valve with the flow path of the Christmas tree upstream of the closure and with the flow conductor; continuing introducing of control fluid through said lateral control fluid passage into the flow conductor to load the well with control fluid to prevent escape of well fluids from the well producing formation through said flow conductor.
 7. A method of controlling flow from a well having a flow conductor therein for conducting well fluids from a producing formation to a surface production flow line through a Christmas tree having a flow path therethrough and having a control valve connected therein with a normally open through flow passage forming a part of the flow path through the Christmas tree and a lateral control fluid passage normally closed off from communication with said through flow passage, which method includes: producing well fluids from the well producing formation through the flow conductor and the flow path through the Christmas tree to the surface production flow line; introducing control fluid under pressure into said lateral control fluid passage of the control valve to operate said control valve automatically by such control fluid pressure to close off flow of well fluids through the flow conductor and the flow path through the Christmas tree to the surface production flow line at a point downstream of said lateral control fluid passage of said control valve and to establish communication of said lateral control fuid passage of said control valve with the flow path of the Christmas tree upstream of the closure and with the flow conductor; continuing introducing of control fluid through said lateral control fluid passage into the flow conductor to load the well with control fluid to prevent escape of well fluids from the well producing formation through said flow conductor. 